First, Javase (18) Map class, Collections class

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1:map (Master)

(1) An object that maps the key to a value. A map cannot contain duplicate keys, and each key can be mapped to at most one value

(2) What is the difference between map and co11 ection?

A:map stores elements that are key-value pairs, unique keys, and values that can be duplicated. Couples on

B:co11ecti. n stores a single occurrence of an element, a sub-interface set element is unique, and a sub-interface list element can be duplicated. Bachelor

(3) Overview of Map Connection denier functions (self-completion)

A: Add Features

B: Delete Feature

C: Judging function

D: Get Features

E: Length function

(4) Traversal of the Map collection

A: Key to find the value

A: Gets the collection of all keys

B: Iterate through the collection of keys to get each key

C: Find the value according to the key to the collection

B: Key-value pair object find key and value

A: Gets the collection of all key-value pairs of objects

B: Iterates over the collection of key-value pairs of objects, getting each key-value pair of objects

C: To get keys and values based on the key value of the object

(5) Practice of HashMap Collection

A:hashmap<string, string>

B:hashmap<integer, string>

C:hashmap<string, student>

D:hashmap<student, string>

(6) Practice of TreeMap Collection

A:treemap<string, string>

B:treemap<student, string>

2:collections (understanding)

(1) is a tool class that operates on a collection

(2) Interview questions: The difference between collection and collections

A:co11ection is the top-level interface of a single-column collection with two sub-interfaces list and set

B:co11ections is a tool class that operates on a collection and can be sorted and looked up

(3) Common several small method (oneself can go API query, the function of each method and arrays similar)

A:public static <T> void sort (list<t> List)

b:public static <r> int BinarySearch (list<?> List, T key)

C:public static <T> T max (collection<?> coll)

D:public static void reverse (list<?> List)

E:public static void Shuffle (List<?> List)

(4) Case

A:arraylist Collection stores the ordering of custom objects

B: Simulated bucket landlord shuffle and licensing

C: Simulate bucket landlord shuffle and licensing and sort cards

First, Javase (18) Map class, Collections class